Ammonium nitrate, kaolin clay, monoamine mixture sensitized with liquid hydrocarbon and preparation



United Sttes This method relates to nitro-carbo-nitrate compositions having improved crystalline stability and relates to a method for the preparation of these materials. In a specific embodiment this invention relates to a material which can be incorporated in industrial grade ammonium nitrate to retard the caking of the ammonium nitrate during its shipping, storage and handling without adversely affecting the crystalline stability of the explosive, i.e., nitro-carbonitrate compositions prepare-d therefrom.

One of the dificulties encountered in the production, handling and storage of ammonium nitrate is caking of the solid. The ammonium nitrate is commonly produced in a prilling tower wherein molten ammonium nitrate is sprayed from the top of the tower and falls to the bottom countercurrent to a stream of drying gases, solidifying in its passage. The pn'lls withdrawn from the tower are thereafter dried and cooled. When these particles are stored for prolonged periods in bulk, or more conventionally, in paper bags, the solid prills tend to cake or adhere together in a solid mass. This caking tendency is undesired since it reduces the free flowing nature of the solids and requires additional handling to break up the agglomerates or cakes formed during the storage and handling.

conventionally, the ammonium nitrate destined for use in explosive compositions, i.e., nitro-carbo-nitrate compositions, is stored, handled and shipped as industrial grade ammonium nitrate. The carbonaceous fuel is added to the nitrate shortly before use of the explosive to avoid shipment of highly sensitive explosive materials. Accordingly, it is important that the solid ammonium nitrate be resistant to the caking and a number of anti-caking agents have been suggested for use. Included in such materials are various surface active agents such as alkaryl sulfonates, heterocyclic nitrogen bases, quaternary ammonium salts, and long chain aliphatic amines such as the C to C aliphatic amines suggested by British Patent 805,112. A material conventionally employed for this use comprises a dimethyl naphthalene sulfonate as well as the sulfonates of rosaniline or pararosaniline.

We have found, however, that the use of the aforementioned surface active materials imparts an undesired friability to the nitro-car-bo-nitrate explosive when the ammonium nitrate is sensitized by the addition of from 5 to weight percent of a carbonaceous fuel. As a result, the nitro-carbo-nitrate compositions prepared from the industrial grade ammonium nitrate having conventionally surface active agents degrade upon storage and this degradation is accelerated where the storage temperature cycles through the ammonium nitrate crystal transition temperature of 90 F.

It is an object of this invention to provide a nitro-carbonitrate composition containing an anti-caking agent which does not adversely affect the friability resistance of the composition during storage.

It is a further object of this invention to provide a method for the production of industrial grade ammonium nitrate containing a suitable anti-caking agent and subsequent sensitization of the material to produce a nitrocarbo-nitrate composition having resistance to crystalline degradation.

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Other and related objects Will be apparent from the following description.

We have now found that the combined use of an aliphatic amine having from 8 to about 22 carbons and a kaolin clay achieves the aforementioned objectives when incorporated with the ammonium nitrate and/or the nitro-carbo-nitrate material in amounts comprising from about 0.1 to about 5.0 weight percent of the final composition.

Our invention thus comprises compositions consisting of ammonium nitrate, a C to C aliphatic monoamine, a kaolin clay and sufficient quantities of a carbonaceous fuel to sensitize the ammonium nitrate. The aliphatic amine is employed in the composition in amounts comprising from about .01 to 1.0 percent and the kaolin clay is employed in amounts comprising from about 0.1 to about 5.0 weight percent of the final composition.

Our invention also comprises a method for the production of sensitized ammonium nitrate or nitro-carbo-nitrate compositions wherein the ammonium nitrate solids are admixed with the aforementioned aliphatic amine and kaolin and the resultant product is handled, stored and shipped prior to its intended destination and, there, sensitized by the addition thereto of a carbonaceous fuel.

The ammonium nitrate used in accordance with our invention therefore comprises conventional industrial grade ammonium nitrate solids which are marketed and handled as particles of diameters from about .01 to about 0.25 inch, usually about 0.05 to 0.1 inch, and bulk densities from about 45 to about 70 pounds per cubic foot. As previously mentioned, to this ammonium nitrate is added a mixture of an aliphatic amine and kaolin clay.

The aliphatic amine can, in general, be any aliphatic, primary, monoamine having 8 to about 22 carbons and can be unsaturated or saturated. Accordingly, any of the following amines can be used: octylamine, octenylamine, nonylamine, laurylamine, decylamine, decenylamine, tetradecylamine, pentadecenylamine, octadecylamine, nonadecylamine, eicosylamine, eicosenylaniine, docosylamine, tricosylamine, tricosenylamine, tetracosylamine, etc. Preferably aliphatic amines having from about 12 to 18 carbons are employed.

The clay employed as the other component of the additive is in general any kaolin or kaolin type material. These clays have in general the following imperical formula:

A1 0 2Si0 ZH O The clays are rich in kaolin minerals including kaolinite, dickite, nacrite, anauxite and hallyosite. The kaolin clays are usually found containing between about 30 and 40 percent Al O and possessing a low cationic base exchange capacity, in the order of about 0.1 to 10 milliequivalents per grams of dry clay. These materials exhibit a diiferential thermal analysis curve having a strong endothermic peak at 620 C. and a strong exothermic peak at 980 C. which sharply differentiates the kaolin clays from other clay mineral groups. The kaolin minerals also possess a two-layer crystal lattice distinguishing these materials from the bentonites and montmorillonites which possess three-layer lattices.

As previously mentioned the aliphatic amine is employed in amounts of between about .01 and about 1.0 weight percent, preferably between about .02 and about 0.08 weight percent of the final ammonium nitrate composition. The clay mineral is employed in amounts between about 0.1 and about 5.0 weight percent, preferably between about 0.5 and about 1.0 weight percent of the same composition. In a preferred embodiment the clay and the aliphatic amine are admixed together and added as a single component to the ammonium nitrate. Consequently, the materials are admixed in the aforemen- C tioned proportions wherein the aliphatic amine comprises from about to about 15 weight percent, preferably from about 8 to about 12 weight percent by weight of the composition of aliphatic amine and kaolin clay.

practice, optional amounts of promoting materials can also be added to the composition, e.g., up to about weight percent of various explosive materials such as nitrocellulose, trinitrotoluene, nitroglycerine, etc.

Our invention will now be described by reference to The aforementioned amine-clay mixture is then ad 5 mixed with the ammonium nitrate solid compositions after the following example: these materials have been formed and preferably after they have been dried and cooled to a temperature less Exami than about 150 F. The prills are commonly dried to mo sture contents of approximately 0.1 to about 1.0 10 Ammonium nitrate prills having approximately 0.15 to weight percent and the additive can be incorporated in 0.3 weight percent moisture content, a bulk density of the sohd mixture prior to or after the drying operation. 48 pounds per cubic foot and average prill diameter of In a suitable embodiment the additive can simply be .06 inch were admixed with the additives indicated in added to the ammonium nitrate in the drier, which is the following table which were employed in the conceneonventionally a rotating drum, and the intimate admix- 15 trati ns also set forth in the table. The compositions were mg of the additive and the ammonium nitrate a hieved thereafter sensitized by the addition of 6 Weight percent by the mixing encountered in this drum. Thereafter, the of a hydrocarbon oil of the identity indicated in the ammonium nitrate can be handled in the conventional table. Thereafter, samples of each of the admixed commanner, including bulk storage under dehumidified air positions were placed in an electric oven controlled at conditions if necessary, and the subsequent bagging and a Constant temperature of 120 F. After 8 hours in the shipment of the material. oven the samples were removed and allowed to gradually Upon arrival at the destination or approximate area cool to about 70 F. Thereafter the samples were again of intended use of the ammonium nitrate as an explosive placed in the electric oven. A single heating and cooling composition, the material is usually stored and, when through the 90 F. transition temperature was recorded needed, is Withdrawn from storage and sensitized by the as one temperature cycle. The samples were inspected addition thereto of from about 2 to about 10 weight after each temperature cycle prior to their return to the percent of a carbonaceous material. oven and when the crystals had degraded into a powder Preferably a liquid carbonaceous material is admixed the number of cycles before such degradation Was re- With the ammonium nitrate and such carbonaceous macorded and this data appears in the table. Under these tenal can be any hydrocarbon liquid. Included as suitable conditions the following data were obtained:

TABLE Organic Agent Solid Test Oil Cycles Before Coneen- Conecn Degradation Identity tration, Identity tration, percent percent 008 0.67 Diesel 18 0.08 0. 67 Redline 80 17 0.0 0.75 Diesel 17 0.0 0. 75 17 0. 04 0. 71 14 0. 04 0.71 14 0. 04 0. 71 14 0. 04 0.71 14 0. 04 0.71 6 0.04 0. 71 Redline s0 4 0.04 O. 71 Bright stock 10 0. 04 0. 71 7 0.08 0. 07 6 0.05 0.0 4 do 0.05 o 0.0 RedlineSO 5 Dimethylnaphthalene su1fonate 0.08 Diatomaceous earth 0. 67 Diesel 4 B A lubricating oil, gravity 27 API, pour point -25 F., flash point 325 F. b A lubricating oil, gravity about 30 API, flash point about 400 F. e A lubricating oil, gravity 25 API, flash point 570 F.

materials are various mineral oil and mineral oil distillates and residues obtained from the fractionation of straight run or converted mineral stocks. Typical materials are crude oil, crude oil disti llates, e.g., naphth-as, kerosene, Diesel oils, light and heavy gas oils, stove oils, and reduced crudes. Similar boiling point range stocks can be obtained from converted, i.e., thermally or catalytically cracked crude oils and crude oil distil'lates. As is Well known in the ammonium nitrate explosive art, the carbonaceous material serves only to provide a fuel for the oxidizing component of the ammonium nitrate composition and therefore any suitable combustible or carbonaceous material can be used and the chemical identity and nature of the carbonaceous material is not critical to the invention. Preferably, however, for ease of preparation, a low viscosity hydrocarbon material is employed such as a kerosene, light or heavy gas oil or Diesel oil. After the selected hydrocarbon has been intimately admixed with the ammonium nitrate and additive composition the resultant material is ready for use as an explosive composition. If desired, in accordance with customary The preceding tabulated data sets forth the results obtainable with our invention. Specifically, Samples 1, 2 and 5 through 8 demonstrate that a high resistance to degradation of the sensitized ammonium nitrate is achieved when the material contains the additive comprising a mixture of fatty amine and a kaolin. Samples 3 and 4 demonstrate the sensitized ammonium nitrate resistance to friability which has no surface active agent incorporated therein.

Although the ammonium nitrate coated with kaolin but having no surface activation incorporated therein is as resistant to friability as the ammonium nitrate which contains our additive, the former material is much less resistant to caking and therefore is not satisfactory for the shipment, storage and handling as commercial grade ammonium nitrate.

The data further demonstratethat conventionally employed additives do not achieve comparable resistances to friability of the sensitized nitro-carbo-nitrate composition. Thus, Tests 9 through 13 demonstrate that a conventionally employed material, e.-g., dimethyl napthalene sulfonate with kaolin fails to impart friability resistance to the sensitized ammonium nitrate product. This tendency is also shown With the combination of dimethyl naphthalene sulfonate and diatomaceous earth and test number 16. Test 14 illustrates that the combined presence of the kaolin and the fatty amine is necessary for the resistance to friability since in the absence of the kaolin the ammonium nitrate containing the fatty amine has a reduced resistance to friability.

The preceding example is intended fully to illustrate the mode of practicing of our invention and to demonstrate results obtainable thereby. It is not intended that the invention be unduly limited to the materials and operation set forth in the example, but rather that the invention be as set forth in the following method and composition claims.

We claim:

1. A solid explosive composition having a high resistance to friability during storage at temperatures which fluctuate about and below 90 F. that consists essentially of ammonium nitrate, from about 2 to about Weight percent of a liquid hydrocarbon carbonaceous fuel, sufficient to sensitize said ammonium nitrate to detonation and from about 0.1 to about 5.0 weight percent of a preformed additive consisting of from 5 to about weight percent of an aliphatic fatty monoamine having from 12 to about 18 carbons and the balance of a kaolin clay.

2. The composition of claim 1 wherein said aliphatic amine is saturated.

3. The method of producing an explosive composition comprising ammonium nitrate sensitized with a liquid hydrocarbon carbonaceous fuel which comprises admixing solid ammonium nitrate prills having particle diameters from about .01 to about 0.1 inch with an additive consisting essentially of from about .01 to about 1.0 Weight percent of a C to C aliphatic primary monoamine and from 0.1 to about 5.0 weight percent of a kaolin clay to prepare a mixture of ammonium nitrate, kaolin clay, monoamine suitable for shipping; thereafter sensitizing said ammonium nitration by the addition thereto from 2 to about 10 weight percent of a liquid hydrocarbon carbonaceous fuel.

References Cited UNITED STATES PATENTS 2,975,046 3/1961 Cooley et a1. 149-46 X 2,976,137 3/1961 Stengel 14946 X 2,978,864 4/1961 Stengel 149-46 X 2,997,378 8/1961 Cox et al. 14946 X 3,039,903 6/1962 Enoksson 14946 X 3,046,888 7/1962 Gordon 14946 3,116,185 12/1963 Wilson et al 14946 X 3,138,496 6/1964 Monical 149-11 BENJAMIN R. PADGETT, Primary Examiner. CARL D. QUARFORTH, Examiner. S. I. LECHERT, Assistant Examiner. 

1. A SOLID EXPLOSIVE COMPOSITION HAVING A HIGH RESISTANCE TO FRIABILITY DURING STORAGE AT TEMPERATURES WHICH FLUCTUATE ABOUT AND BELOW 90*F. THAT CONSISTS ESSENTIALLY OF AMMONIUM NITRATE, FROM ABOUT 2 TO ABOUT 10 WEIGHT PERCENT OF A LIQUID HYDROCARBON CARBONACEUS FUEL, SUFFICIENT TO SENSITIZE SAID AMMONIUM NITRATE TO DETONATION AND FROM ABOUT 0.1 TO ABOUT 5.0 WEIGHT PERCENT OF A PREFORMED ADDITIVE CONSISTING OF FROM 5 TO ABOUT 15 WEIGHT PERCENT OF AN ALIPHATIC FATTY MONOAMINE HAVING FROM 12 TO ABOUT 18 CARBONS AND THE BALANCE OF A KAOLIN CLAY.
 3. THE METHOD OF PRODUCING AN EXPLOSIVE COMPOSITION COMPRISING AMMONIUM NITRATE SENSITIZED WITH A LIQUID HYDROCARBON CARBONACEOUS FUEL WHICH COMPRISES ADMIXING SOLID AMMONIUM NITRATE PRILLS HAVING PARTICLE DIAMETERS FROM ABOUT .01 TO ABOUT 0.1 INCH WITH AN ADDITIVE CONSISTING ESSENTIALLY OF FROM ABOUT .01 TO ABOUT 1.0 WEIGHT PERCENT OF A C12 TO C18 ALIPHATIC PRIMARY MONOAMINE AND FROM 0.1 TO ABOUT 5.0 WEIGHT PERCENT OF A KAOLIN CLAY TO PREPARE A MIXTURE OF AMMONIUM NITRATE, KAOLIN CLAY, MONOAMINE SUITABLE FOR SHIPPING; THEREAFTER SENSITIZING SAID AMMONIUM NITRATION BY THE ADDITION THERETO FROM 2 TO ABOUT 10 WEIGHT PERCENT OF A LIQUID HYDROCARBON CARBONACEOUS FUEL. 